1. Field of the Invention
The present invention relates to an image recording apparatus such as a printer, a copying apparatus or a facsimile, having a cutting unit for cutting a roll-shaped recording medium.
2. Description of the Related Art
There are already commercially available image recording apparatuses having a printer function for recording an image on a recording medium based on image information, composite apparatuses having a facsimile function, an original reading function, an image pickup function and the like in addition to the printer function, and systems constituted by connecting such image recording apparatuses to host equipment such as computers.
The image recording apparatus employed in such apparatuses sometimes performs image recording on a roll-shaped recording medium such as a recording paper or a recording film. In the present application, a “rolled sheet” may be defined as a roll-shaped recording medium, and further the material thereof is not limited to a paper or a plastic sheet.
An image recording apparatus for image recording on a roll-shaped recording medium may include a cutting unit (cutting mechanism) for cutting the recording medium. As for the cutting unit, there is already known an apparatus for cutting the recording medium by a pair of cutting blades. Such cutting unit is used, for example in an image recording apparatus for image recording on a roll-shaped recording medium conveyed in the apparatus, for cutting the recording medium after recording into a predetermined length at a discharge thereof. Such cutting units may include a type utilizing a knife-shaped blade, a type utilizing a pair of blades of which one is an elongated fixed blade and the other is a rotatable circular blade, and a type utilizing a pair of rotatable circular blades.
Such image recording apparatuses are constructed so as to store a roll-shaped recording medium, to record image data by a scanning (reciprocating) motion of a recording head, and to cut the recording medium after image data recording into each page. More specifically, the recording medium is supplied to a platen when image data are entered. Above the platen, there is provided a recording head for executing a recording by ink discharge under a reciprocating motion. An image of a line is recorded on the recording medium by a scanning motion of the recording head, and, after the recording medium is advanced by a predetermined distance by a conveying roller, an image of a line is recorded again by a scanning motion of the recording head. Thus an image is recorded on an entire page by repeating the recording of a line image and the conveying of the recording medium by a predetermined distance. Then a recorded portion of the recording medium is guided to a sheet discharge member provided outside the apparatus, and is cut into each page by the cutting unit. The recording medium cut into each page is stored on a stacking member provided below the sheet discharge member.
In the case of cutting the recording medium in the serial operations as described above, the cutting operation is executed from a lateral end of the recording medium to the other lateral end thereof, and, in case the recording medium has a large width, an already cut portion of the recording medium may be displaced downwards by the weight thereof in the course of the cutting operation. For this reason, the recording medium may not be cut linearly but may show a curved cut edge or may be torn off at an end portion of the cut edge.
In order to prevent such a situation, Japanese Patent Application Laid-Open No. H05-147385 discloses a structure for pressing, at the cutting of the recording medium, a position thereof at a sheet discharge side with respect to a cutting line by a lower end of a cover, thereby, preventing a displacement of the recording medium and enabling an exact cutting of the recording medium.
Also Japanese Patent Application Laid-Open No. H05-254194 discloses a structure of extending, at the cutting of the recording medium, a pressing belt for pressing the recording medium along with the movement of a cutter unit, thereby, preventing a displacement of the recording medium and enabling an exact cutting of the recording medium.
Moreover, Japanese Patent Application Laid-Open No. H11-78140 discloses a structure for pressing, at the cutting of the recording medium, a lateral edge at the cutting start side, thereby, preventing a displacement of the recording medium and enabling an exact cutting of the recording medium.
However the structure disclosed in Japanese Patent Application Laid-Open No. H05-147385 is associated with several technical drawbacks. For instance, the pressing member has to be separated from the recording medium at the conveying motion thereof and to be pressed thereon at the cutting operation. Moreover, the pressing member, formed by a cover, provides a bulky and complex apparatus with an elevated cost. Also, since the recorded surface (image bearing surface) of the recording medium has to be pressed, the recorded image may be damaged in case of recording a frameless image.
Also, the structure disclosed in Japanese Patent Application Laid-open No. H05-254194 is associated with a drawback. In particular, since the recorded surface has to be pressed with the pressing belt, the recorded image may be damaged in case of recording a frameless image.
Additionally, the structure disclosed in Japanese Patent Application Laid-open No. H11-78140 has some disadvantages. For instance, it requires a mechanism which separates a pressing member from the recording medium when it is conveyed and which presses the recording medium from above at the cutting operation of the recording medium. Such structure is associated with drawbacks of requiring a complex mechanism with an increased cost, and therefore, since the recorded surface has to be pressed, the recorded image may be damaged in case of recording a frameless image.